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Tuesday, January 21, 2014

Triggering drug release with light

Some illnesses are best treated by the periodic release of drugs into the patient’s bloodstream. Take diabetes, for example. A patient can’t just take his yearly supply of insulin all at once, treating the disease is a continuous and ongoing process.

This leads to two problems. First, depending on the illness, it can be complicated, expensive and/or invasive to monitor and maintain the right dosage of medicine coursing through a patient’s body. And second, the patients themselves have to be compliant, not purposefully or accidentally skipping doses.

But what if you could eliminate both problems by implanting a remotely controlled device to release the medicine that was triggered by light? 

Researchers led by Brian Timko of Harvard Medical School and MIT have developed a gold nanoparticle membrane that becomes porous only when irradiated with near infra-red light. Light at the right wavelengths causes the network of polymers in the membrane to collapse. After the light source is removed, the membrane reforms. If you enclose medicine within these membranes, you have a device that will release those drugs when you expose it to light.

Diabetic rats were implanted with devices containing a synthetic form insulin. The devices were triggered either by exposure to light or by immersing the rats in a very hot bath. As hoped, insulin was released into the rats’ bodies from the now permeable membranes. The devices could be retriggered every day for at least five days, continuing to release more medicine.

Obviously, this is in the ‘proof of concept’ stage. No one is going to say, “it’s too arduous to remember to take my pills, so instead I’ll have them implanted and stand under a special light four times a day.” It’s not even clear to me who would be responsible for doing the triggering, the doctors or the patients themselves. Nevertheless, this technique does have tremendous potential, especially for patients who require long-term medication.

Brian P. Timko, Manuel Arruebo, Sahadev A. Shankarappa, Brian McAlvin, & et al (2013). Near-infrared–actuated devices for remotely controlled drug delivery Proceedings of the National Academy of Sciences of the United States of America : doi/10.1073/pnas.1322651111.